As earlier reported by KickOff.com, Buchanan has impressed enough to land a two-year deal, with the option of a further year, with the Team of Choice after parting ways with Amakhosi last month.
Having made just 10 appearances in his two years at Naturena, the 27-year-old central midfielder was invited for a 10-day assessment by the club.
It is now apparent that the former Bloemfontein Celtic playmaker has been cleared of any long-term damage that reportedly hampered his chances of game-time under ex-Chiefs coach Steve Komphela.
"It's a new start for me and I'm excited to be here. It's a good team, a good coach, good supporters and structures, and a good style of play," Buchanan told the club.
"Coach Fadlu [Davids] is one of the main reasons I have joined the club. The way the team plays, the style of coaching, the fact that he knows what I can do and where he can improve me, so I am very excited about that."
Coach Fadlu Davids added: "I think Keagan will give us a different dimension in midfield. He will compliment our playing style well."
Buchanan will likely make his first public appearance in the colours of Maritzburg when they take part in the 2018 Premier Cup, which features all Absa Premiership and First Division teams from KwaZulu-Natal, later this month.
The 2018/19 domestic campaign is scheduled to kick off on the weekend of August 3-5, pending the outcome of the ongoing Ajax Cape Town/Tendai Ndoro saga.